The proposed goals of this project for the next fiscal year are: (1) To isolate type C viruses from normal human tissue and/or tumor specimens and examine them as possible candidates for the causative agent in human cancer, (2) To determine if antibodies to type C viruses can be located in the serum of normal subjects or patients with neoplasia, and (3) To further characterize the cellular regulation of known mammalian endogenous type C viruses.